ZOJ 2859 Matrix Searching（二维线段树）

const int INF=1000000000;
const int N=305;

struct node
{
int Min,x[2],y[2],son[4];
node(){}
node(int x0,int y0,int x1,int y1)
{
x[0]=x0;
x[1]=x1;
y[0]=y0;
y[1]=y1;
Min=INF;
clr(son,0);
}
};

node a[N*N*5];
int e,n,b

;
int C;

void up(int t)
{
int i;
FOR0(i,4)
{
a[t].Min=min(a[t].Min,a[a[t].son[i]].Min);
}
}

void build(int t,int x0,int y0,int x1,int y1)
{
a[t]=node(x0,y0,x1,y1);
if(x0==x1&&y0==y1)
{
a[t].Min=b[x0][y0];
return;
}
int i;
FOR0(i,4) a[t].son[i]=++e;
int midX=(x0+x1)>>1;
int midY=(y0+y1)>>1;
int midX1=midX<x1?midX+1:midX;
int midY1=midY<y1?midY+1:midY;
build(a[t].son[0],x0,y0,midX,midY);
build(a[t].son[1],x0,midY1,midX,y1);
build(a[t].son[2],midX1,y0,x1,midY);
build(a[t].son[3],midX1,midY1,x1,y1);
up(t);
}

int query(int t,int x0,int y0,int x1,int y1)
{
if(x0>a[t].x[1]||x1<a[t].x[0]||y0>a[t].y[1]||y1<a[t].y[0])
{
return INF;
}
if(x0<=a[t].x[0]&&x1>=a[t].x[1]&&y0<=a[t].y[0]&&y1>=a[t].y[1])
{
return a[t].Min;
}
int ans=INF,i,temp;
FOR0(i,4)
{
temp=query(a[t].son[i],x0,y0,x1,y1);
ans=min(ans,temp);
}
return ans;
}

int main()
{
RD(C);
while(C--)
{
RD(n);
int i,j;
FOR1(i,n) FOR1(j,n) RD(b[i][j]);
build(0,1,1,n,n);
int x0,y0,x1,y1,m;
RD(m);
while(m--)
{
RD(x0,y0);
RD(x1,y1);
PR(query(0,x0,y0,x1,y1));
}
}
return 0;
}